Air intakes for gas turbine engines

Abstract

An inlet particle separator for a gas tubine engine, comprises, (a) an annular air inlet duct, (b) downstream of the inlet duct an annular obturating member having a continuous surface, the menber arranged to bifurcate the inlet duct into annular compressor and scavenge ducts, the compressor duct leading downstream to an engine compressor stage, the scavenge duct being located radially inwardly of the compresor duct and directed upstream thereof, and arranged to scavenge solid matter from the air flow through the inlet duct. The inlet duct is provided with an annular constriction at its downstream end extending radially inwards from a radially outer wall of the inlet duct. The inlet duct is angled so as to direct incoming air against the obturating member, the arrangement of the obturating member, the inlet duct, and the constriction being such as to prevent line-of-sight viewing of the compressor duct from the inlet duct and to deflect solid matter colliding with the walls of the inlet duct into the scavenge duct.

I claim: 
     
       1. An inlet particle separator for a gas turbine engine, the separator comprising: (a) an annular air inlet duct, (b) downstream of the inlet duct and extending radially outwards from the engine axis an annular web-form obturating member having a continuous surface, the member arranged to bifurcate the inlet duct into first and second annular ducts, the first annular duct leading downstream to an engine compressor stage, the second annular duct being located radially inwardly of the first annular duct and directed upstream thereof, and arranged to scavenge solid matter from the air flow through the inlet duct, wherein the inlet duct is provided with an annular constriction at its downstream end, the constriction extending radially inwards from a radially outer wall of the inlet duct, the inlet duct further being angled so as to direct incoming air against the obturating member, the arrangement of the obturating member, the inlet duct, and the constriction being such as to prevent line-of-sight viewing of the first annular duct from the inlet duct and to deflect solid matter colliding with the walls of the inlet duct into the second annular duct. 
     
     
       2. An inlet particle separator as claimed in claim 1 wherein the obturating member is positioned at an acute angle relative to the longitudinal axis of the engine in a direction towards the air inlet end of the engine. 
     
     
       3. An inlet particle separator as claimed in claim 1 wherein the radial distance of the annular periphery of the obturating member from the longitudinal axis of the engine is at least equal to the minimum axial distance of the annular constriction from the engine longitudinal axis. 
     
     
       4. An inlet particle separator as claimed in claim 1 wherein the second annular duct is provided with a restriction at its inlet.